/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.coders;



import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.math.BigDecimal;

import java.math.BigInteger;

import java.math.MathContext;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkNotNull;



/**

 * A {@link BigDecimalCoder} encodes a {@link BigDecimal} as an integer scale encoded with {@link

 * VarIntCoder} and a {@link BigInteger} encoded using {@link BigIntegerCoder}. The {@link

 * BigInteger}, when scaled (with unlimited precision, aka {@link MathContext#UNLIMITED}), yields

 * the expected {@link BigDecimal}.

 */

public class BigDecimalCoder extends AtomicCoder<BigDecimal> {



  public static BigDecimalCoder of() {

    return INSTANCE;

  }



  /////////////////////////////////////////////////////////////////////////////



  private static final BigDecimalCoder INSTANCE = new BigDecimalCoder();



  private static final VarIntCoder VAR_INT_CODER = VarIntCoder.of();

  private static final BigIntegerCoder BIG_INT_CODER = BigIntegerCoder.of();



  private BigDecimalCoder() {}



  @Override

  public void encode(BigDecimal value, OutputStream outStream) throws IOException, CoderException {

    encode(value, outStream, Coder.Context.NESTED);

  }



  @Override

  public void encode(BigDecimal value, OutputStream outStream, Coder.Context context)

      throws IOException, CoderException {

    checkNotNull(value, String.format("cannot encode a null %s", BigDecimal.class.getSimpleName()));

    VAR_INT_CODER.encode(value.scale(), outStream);

    BIG_INT_CODER.encode(value.unscaledValue(), outStream, context);

  }



  @Override

  public BigDecimal decode(InputStream inStream) throws IOException, CoderException {

    return decode(inStream, Coder.Context.NESTED);

  }



  @Override

  public BigDecimal decode(InputStream inStream, Coder.Context context)

      throws IOException, CoderException {

    int scale = VAR_INT_CODER.decode(inStream);

    BigInteger bigInteger = BIG_INT_CODER.decode(inStream, context);

    return new BigDecimal(bigInteger, scale);

  }



  @Override

  public void verifyDeterministic() throws Coder.NonDeterministicException {

    VAR_INT_CODER.verifyDeterministic();

    BIG_INT_CODER.verifyDeterministic();

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code true}. This coder is injective.

   */

  @Override

  public boolean consistentWithEquals() {

    return true;

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code true}, because {@link #getEncodedElementByteSize} runs in constant time.

   */

  @Override

  public boolean isRegisterByteSizeObserverCheap(BigDecimal value) {

    return true;

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code 4} (the size of an integer denoting the scale) plus {@code 4} (the size of an

   *     integer length prefix for the following bytes) plus the size of the two's-complement

   *     representation of the {@link BigInteger} that, when scaled, equals the given value.

   */

  @Override

  protected long getEncodedElementByteSize(BigDecimal value) throws Exception {

    checkNotNull(value, String.format("cannot encode a null %s", BigDecimal.class.getSimpleName()));

    return VAR_INT_CODER.getEncodedElementByteSize(value.scale())

        + BIG_INT_CODER.getEncodedElementByteSize(value.unscaledValue());

  }

}